Motor-control system



May 15, 1923.

Original Filed March 15, 1920 E -j m 0 Illl I 8 9 n WITNESSES:

Ai'TORNEY Patented May 15, 1923.

UNITED HENRY D. JAMES, OF EDGEXVGGD 1 ELK,

F l t: E.

PFNl'JSE "LVANIA, ASSIG-NOR TO WESTING- ti u HOUSE ELECTRIC &, IJZANUFACTU NG COIVZPANY, A CQRPORATION 0F PENNSYL- VANIA.

IEOTGE-CGNTROL SYSTEM.

Original application filed March 13, 1920, Serial No. 365,428?

To all whom it may concern:

Be it known that I, HENRY D. JAMns, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Motor-Control Systems, of which the following is a specification, this application being a division of copending application Serial No. 365,467, filed March 13, 1920.

My invention relates to motor-control sys tems and particularly to such systems as are employed to effect the dynamic braking oi? series electric motors.

One object of my invention is to provide a dynamic brake for rapidly diminishing the speed of rotation of a series electric motor with the least possible wear and. injury thereto.

A second object of my invention is to pro vide a system wherein a master switch may be quickly thrown from an operative position to a position corresponding to the re verse direction of operation of the motor without injury thereto.

In a system embodying my invention, the same number of contactors are (iiDplO tCl as are used with a standard reversing con troller, and dynamic braking is elii ected by employing a dynamic brakingcircuit which includes a resistor, switches that coact with the directional switches, main-line switch, and a circuit including a switch wh ch 111 coact with the directional switches or the main-line switch for energizing the series field magnet winding during dynamic braking.

In the accompanying drawing, Fig. 1 is a diagrammatic View of circuits and apparatus embodying my invention;

Fig. 2 is a schematic diagram correspou l ing to Fig. 1, and

Fig. 3 is a sequence chart indicating the sequence of operation of the several con tactors provided for controlling the. respective circuits and apparatus shown in the drawing.

Referring to the drawing, line conductors I 1 and 2, which may be connected to any suit able source of energy, supply current to an electric motor, the armature of which is indicated at 3 and which has a series fieldmagnet winding i. A starting resistor 5 is in series with the motor. If it is so desired,

Divided and this application filed August Serial No. 583,508.

a portion or all of the resistor 5 may be shunted during the normal operation oi the motor, but such arrangement is not material to the present invention.

The direction of operation of the motor is controlled by the directional switches 6, 7, 8 and 9. A dynamic-braking circuit comprises pair of auxiliary switches 10 and 11 which are mechanically interlocked with re-- switches 6 and 7, respectively, and resistors 12. A main-line switch 13 is provided with an operating coil 14.

A master switch 16 comprises electricallyconnected contact segn'ieiits 17, 18 and 19 respectively engage contact fingers 20, 1 and when they are moved to forward position (4, thereby energizing actuating coils 23, 2d and 14 ot the respective switches 9. 7 and 13. The contact fin er 29. is supplied. with electrical energy Irom the line cond ctor 'l. Contact lingers 29., and 26 respectively coact with electrically-connected contact segments 27, 28 and 29 to control the actuating coils 30 and 31 of switches S and 6, respectively, in the reverse position C.

The dynamic-braking switches 10 and 11 have holding coils 32 and 33, respectively. Switches 10 and 41 are mechanically interlocked, respectively, with rcmrsing switches 8 and 9. By means of the auxiliary switch it). the control circuit, which includes contact finger 26 and the coils 81 and 141:, cannot be completed until the switch 8 is closed, As the coils 31 and 1 1- res jiectively actuate switches 6 and it is impossible to close switch 6 without first closing switch 8 and, it switch 6 is closed. switch 13 must be closed. in a similar manner, switch 41 prevents switch 7 from closing until switch 9 is closed and, ii" switch 7 is closed, switch 13 must also he closed.

When the master switch is in position (1 the contact segments 17, 18 and 19 are engaged, respectively, by contact fingers 20, 21 and 22, and thus the coils 23, 24 and 1 1 are energized to (.lOfrifi directional switches 9 and T and the line switch 13, thereby causingg the motor to rotate in the reverse direction. Dynamic-braking switch 11 is opened by the closing of? the switch 7, and the reversing switches 6 and 8 are held open by gravity when the coils 81 and 30 are not energized.

It the master switch be moved to posi tion a, which is both the drift and the off position, the contact fingers Qt), s1 and 22 are disengaged from the corresponding contact segments 17, 18 and 19, thereby tie-energizing coils 2 and 14, and thus opening: switches 9, 7 and 13. In this position, the dynamic-braking switches 10 and 11 only are closed.

If it is desired to employ the motor for dynamic braking, when the armature 3 s rotating in the reverse directioi'i. the ma ter switch is moved to position (1. Tu position, the contact tingea 22 and gage contact segments 27 and ther: energizing coil 80, which actuatcs reversing switch 8. The dynamic-brainng switches 10 and 11 being closed, w ll as d.,'ertion switch 8, a complete generator circuit is established. The current generated by the armature 3 traverses acircuit comprising the switch 8, the winding 4, the resistor 12 the switch 10 to the armature 3, and through a second circuit comprising switch ll, both banks of resistance 12 the switch 10 to the armature 3. The electrical. energy generated by the motor is expended in the resistors 12.

By moving the master switch from position (6 to position c, the circuits are arranged for the forward direction of rotation of the motor. The contawt linger 2&5 enga' s the contact segment 29, thus energizing coils 31 and 14, which actuate switches (3 and 1.3. The switches 6, S and 13 being closed, and the remaining" switches beino open with th exception of the dynamic-braking switch l. and the auxiliary switch 4-0, the motor rotates in a forward direction.

If dynamic braking is desired, when the motor is rotating in a forward directi' n, the master switch is moved in a reverse duection from position to position b. All

of the switches, except dynamic-bralri .51- switches 10 and i i, are released as the (011" tact fingers pass through the otl iosition 0. At position b, the contact lingers 20 and 22 engage the contact segments i7 and 19, thereby energizing the actuating coil 23 and closing the switch 9. i

I have invented a system of control in which a series motor may be permitted to drift before dynamic braking is applied. This order in the sequence of operation of the motor is desirable, for the operator of a car or machine, by permitting the moto to drift and then applying dynamic bra hing, can bring the car or machine to a op nearer a predetermined point, than, it dynamic braking first occurs. It is apparent that power and wear on the equiinneat are lessened by having drifting precede dynamic braking of the motor.

In this system, dynamic braking is secured without plugging the motor. 'llnbrcforc. the car or machine will not reverse its direction after coming to a complete stop, as would occur in the systems of control for series motors formerly employed.

I have shown the dynamic braking positions of the master switch nonadjaccnt to heir corresponding perative positions, therefore, dynamic bralrii'ig does not occur, if the master switch is slightly removed from one of the operative positions and the direction of operation of the motor can he quickly changed by continuing the movement of the master switch to its next position.

From the construction and operation of my control system herein described, it is apparent that the principal advantages are the simplicity of contro from the master switch and that quick dynamic braking is secured.

While I have shown a preferred form of my invention, it is apparent that slight modifications may be made without departing from the spirit thereof, I desire, therefore, to be limited only by the scope of the appended claims.

I claim as my invention:

1. The comhinatitm with an electric motor having a series field n'iagnet winding, of a dynamic braking resistor and means for connecting the resistor and field-n'iagnet win L ing in shunt relation during dynamic braking.

2. The combination with an electric motor having a series field-magnet winding and GlOCtl'O-TQSPOllSlV0 controlling means therefor, of a normally closed dynamicdiraking circuit and means comprisii said controlling means for connecting the tiehl-magnu-t winding into the braking circuit.

The combination with an electric motor having an armature, and a field-magne winding, of electro-responsire coi'ltrolling means therefor, a plurality of dynamic oral;- ing resistors norn'ially in circuit with the armature, and means con'lprising said controlling means for connecting the ticld-m:-.;1- netwinding, selectively in circuit with said resistors.

i. In a motor-control system, the combination with a series motor having an armature and a field-magnet winding, and dilertionnl switches tl'rerefor, oi means for connecting said armature and said field-magnet winding in a dynamic braking circuit comprising only one of the said directional switches.

in a motor-control system, the combination, with a series motor having an armature and a field-magnet winding, and direcs tional switches therefor, of means for connecting said armature and said field-magnet winding in a dynamic braking circuit comprising only one of the said directional switches, said motor during dynamic braking being independent of an external source of energy.

6. In a motor-control system, the combination with a series motor having an armature and a field-magnet winding and directional switches therefor, of a dynamic-braking circuit comprising said armature for efiecting dynamicdoraking thereof, and a plurality of switches coacting with said directional switches for controlling said circuit, and so connecting said braking circuit through only one of said directional switches to said field-magnet winding that said winding is energized by said braking circuit.

7. In a motor-control system, the combination with a series motor having 21 heldmagnet winding, a plurality of directional switches for controlling the direction of operation of said motor, and a dynamic-braking circuit for said motor, of a circuit including said series field-magnet winding, and a portion of said dynamic-braking circuit, the direction of the energization of said field magnet winding being controlled by Said directional switches.

S. In a motor-control system, the combination with an electric motor, of controlling means therefor comprising a master switch having an inoperative position, operative positions corresponding to the rotation of said motor in a forward and a reverse direction and intermediate positions for effecting dynamic braking of said motor, and means controlled thereby in such manner that dynamic braking in one direction is accomplished by said master switch being actuated through the adjacent intermediate position and said inoperative position to the other intermediate position.

9. In a motor control system, the combination with a motor and means comprising a plurality of contactors for governing said motor, of a master switch for controlling said contactors and having an inoperative position and operative positions corresponding to the rotation of said motor in a forward and in a reverse direction and intermediate positions for effecting dynamic braking of said motor so arranged that dynamic braking in one direction is accomplished by said master switch being brought to said intermediate position adjacent to said opposite operative position.

10. In a control system, the combination with a motor and means comprising a plurality of contractors for governing said m0- tor, of a master switch for controlling said contactors and having operative positions for effecting the forward and the reverse operation of a motor, a central position for effecting drifting and de-energization of said motor and dynamic-braking positions each of which is between said central position and said opposite operative position.

11. In a motor-control system, the combination with an electric motor, of controlling means therefor comprising a master switch having a central inoperative position, an operative position on each side of the inoperative position, said operative positions corresponding to the respective directions of rotation of said motor, and having, also, a position intermediate each operative position and the inoperative position, each of said intermediate positions being arranged to effect dynamic braking of .said motor when it is rotating in the direction corresponding to the operative position adjacent to the other intermediate position.

12, In a motor-control system, the combination with an electric motor, of controlling means therefor comprising a master switch having a central inoperative position, a position for efiecting dynamic braking of said motor when rotating in the reverse direction, an operative position for efiecting forward rotation of said motor, said positions being in the order named from said central position, and similar positions in the same order from said central position for respectively effecting dynamic braking of said motor when rotating in the forward direction and effecting rotation of said motor in the reverse direction.

13. In a motor-control system, the combination with a motor having an armature and a series field-magnet winding, of a resistor, a plurality of directional contactors for governing the direction of said motor and means comprising said resistor and only one of said directional contactors for forming two dynamic-braking circuits, each of said circuits comprising different portions of said resistor.

In testimony whereof, I have hereunto subscribed my name this 16th day of August, 1922.

HENRY D. JAMES. 

